What is Solved Example on Probability-3

Two coins are tossed. What is the probability of coming up of two heads, if it is known that at least one head comes up?

Sol. When two coins are thrown, let S be the sample space and

A = the event of coming up of two heads

B = the event of coming up of at least one head

Then S = {(H, H), (H, T), (T, H), (T, T)}

A = {(H, H)} and B = {(H, H), (H, T), (T, H)}

\ n(S) = 4, n(B) = 3, n(A) = 1

Also A ∩ B = {(H, H)} \ n(A ∩ B) = 1

Now P(B) = n(B) / n(S) = 3/4 and P(A ∩ B) = n(A ∩ B) / n(S) = 1/4

Required probability, P(A/B) = P(A ∩ B) / P(B) = 1/4 / 3/4 = 1/3

Second Method:

P(A/B) = n(A ∩ B) / n(B) = 1/3

Live Online Email Based Homework Assignment Help in Conditional Probability

Transtutors comprises highly qualified and certified teachers, college professors, subject professionals in various subjects like statistics etc. All our statistics tutors are highly experienced and can clear your doubt regarding conditional probability and can explain the different concepts to you effectively.